Dark rock pro 4 135mm fan not maxing

Wonderrun · 19 Feb 2021 at 19:51

My dark rock pro 4 135mm fan isn't maxing it out it's speed, infact it's barely roatates at 216rpm even when cpu is hot, the 120mm fan is ok.

I have the fans on the provided splitter, going into cpu_opt socket.

I run asus suite 3 with fan expert 4 and chose "standard" profile.

How can get this fan to work better?

My motherboard is an asus crosshair dark hero pro, the case is a be quiet 900 pro rev 2.

Hotwired · 19 Feb 2021 at 20:24

So if you've plugged it into the CPU_OPT then what's plugged into the CPU_FAN header next to it.

I'd plug it into the CPU_FAN or ditch the splitter and plug each cooler fan into one of those two.

If you want to see how fast they go then stop being on standard profile and go to full speed.

If you want it to spin up more than it does then put it on turbo.

If you want to customise the speed curve then select the cpu fan graph and change the dots on it.

Wonderrun · 20 Feb 2021 at 05:25

I may have been reading it wrong as to what fan it is, will have to check later as I'm away from pc right now.

But my setup for fans is I have the 2 dark rock pro 4 fans on a splitter going to cpu_fan, I have 3 case fans, 2 at front, 1 at rear.

Those case fans are connected to the PCB fan controller which is in the be quiet 900 rev 2 case, that in turn is connected to cpu_opt.

Now when i run hwmonitor software it only shows 3 fans, the middle of the 3 fans is usually the one with very low rpm, but which fan that is is hard to say untill I unplug it later.

There also seems to be no way of controlling cpu_opt, nothing in bios, it just lists cpu_fan plus the chassis ones and a couple of other water ones.

I don't get how it's just showing 3 fans when I have a total of 5, maybe it's reading the splitter on the cooler as 1, but that would make 4 I should see in hwmonitor.

If that's the case then 3 fans on the PCB fan controller going to cpu_opt should be read as 1 only aswell?? Making a total of 2. But I see 3 in hwmonitor software, I don't get how it shows 3 unless those 3 are the case fans, pretty confused.

As far as being on standard mode, the fans will ramp up but whichever fan doesnt appear to be ramping up still won't. There's no way I'm going to run on full speed, the amount of noise is like a server farm.

Forgot to mention, running on a 5800x.

Hotwired · 20 Feb 2021 at 07:45

CPU_OPT is not a real fan header, it is a built in fan splitter for when you have two fans on your cpu cooler. It copies CPU_FAN.

All fan splitters or controllers make all fans connected read as one fan because it is not possible to read the RPM of more than 1 fan through a header so the RPM of one fan gets read and the rest are ignored.

If you're seeing a low rpm it's probably because you have the 135mm fan plugged into the 4 wire side of the fan splitter. If you want to see a higher rpm then swap the 120mm fan into the 4 pin side and it will give feedback from that.

Wonderrun · 20 Feb 2021 at 08:12

I'll try that but isn't the splitter 4 wires on each one anyway?

Wonderrun · 20 Feb 2021 at 12:16

Ok so I kind of figured out where I was going wrong, partly anyway. I was reading the info in Hwmonitor wrongly.

I read it as 3 fans but it's intact 1 fan it shows, with reading of "value" "min" "max", I didn't notice that and just looked at the readings as 3 fans.

One of those days.

I've now messed around a bit unplugging the cpu_opt for the 3 case fans but to my suprise they still spun, I could control them via fan controller on the front of the case, not something I really want to do but nice to have. I just thought they wouldn't work if not plugged into cpu_opt.

Only other thing is that if I do use the front panel controller on case, it won't ramp up the dark rock 4 fans, just the case fans, guess it would need to be connected to that controller.

So in the end I think it's working correctly after all if cpu_fan controls cpu_opt, that's obviously why I only see 1 fan listed in hwmonitor and bios.

Thanks for the suggestions